R help - Jan 2004 - Levels number of a factor object

Hi all!

    How to retrieve the levels number of a factor object?
    See this code:
    groups<-gl(4,10)
    I want to retrieve the number of levels (4) of my object "groups"
    I tried groups.levels but this don't work

    Thanks


Laurent Houdusse 
Analyste Programmeur

On Fri, 2004-01-23 at 08:24, Laurent Houdusse wrote:
> Hi all!
> 
>     How to retrieve the levels number of a factor object?
>     See this code:
>     groups<-gl(4,10)
>     I want to retrieve the number of levels (4) of my object
"groups"
>     I tried groups.levels but this don't work
> 
>     Thanks
> 
> 
> Laurent Houdusse 
> Analyste Programmeur

Use nlevels() for the number of levels and levels() to get the actual
level values:
> groups <- gl(4, 10)
> groups
 [1] 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 4 4 4
[35] 4 4 4 4 4 4
Levels: 1 2 3 4
> nlevels(groups)
[1] 4
> levels(groups)
[1] "1" "2" "3" "4"

See ?nlevels and ?levels for more information.

HTH,

Marc Schwartz

r-help-bounces at stat.math.ethz.ch wrote on 23/01/2004 15:24:21:
>
> Hi all!
>
>     How to retrieve the levels number of a factor object?
>     See this code:
>     groups<-gl(4,10)
>     I want to retrieve the number of levels (4) of my object
"groups"
>     I tried groups.levels but this don't work
Is

length(levels(groups))


what you were looking for ?


HTH,

Tobias

> groups<-gl(4,10)
 > levels(groups)
[1] "1" "2" "3" "4"
 > length(levels(groups))
[1] 4

      Is this what you want? 
      spencer graves

Laurent Houdusse wrote:
>Hi all!
>
>    How to retrieve the levels number of a factor object?
>    See this code:
>    groups<-gl(4,10)
>    I want to retrieve the number of levels (4) of my object
"groups"
>    I tried groups.levels but this don't work
>
>    Thanks
>
>
>Laurent Houdusse 
>Analyste Programmeur
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>  
>

Laurent Houdusse <l.houdusse at cerep.fr> writes:
> Hi all!
> 
>     How to retrieve the levels number of a factor object?
>     See this code:
>     groups<-gl(4,10)
>     I want to retrieve the number of levels (4) of my object
"groups"
>     I tried groups.levels but this don't work
> 
>     Thanks
Do you mean just

length(levels(groups))

?

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907

Laurent Houdusse schrieb:
> Hi all!
> 
>     How to retrieve the levels number of a factor object?
>     See this code:
>     groups<-gl(4,10)
>     I want to retrieve the number of levels (4) of my object
"groups"
>     I tried groups.levels but this don't work
Simply try:

length(levels(groups))

Thomas P.